Why the P&L number on your app never feels quite right
You bought Ethereum three times, at three different prices. You sold a little. You paid a fee each time. Now your portfolio says you are up $340. Is that right?
If you have ever stared at a P&L number and thought "where did that come from," you are not alone. Profit and loss math on crypto is simple in theory and messy in practice, mostly because the numbers depend on which accounting method the app uses — and most apps never tell you.
The three numbers Coinlio tracks per coin
Every coin in your portfolio has three cornerstone numbers. Every other P&L number is built from these.
- Quantity held — how many units of the coin you currently own.
- Invested (cost basis) — how much you paid, in total, for the quantity you still hold.
- Current value — quantity × current market price.
From there:
- Unrealized P&L = current value − invested
- Unrealized P&L % = unrealized P&L ÷ invested
"Unrealized" just means you have not sold yet. Once you sell, that portion becomes realized P&L and stops changing.
The method Coinlio uses today — average cost
When you buy the same coin more than once, we blend the prices into a single average. That average becomes the cost basis for every unit you hold. When you sell, we subtract at that average.
Here is the formula, then the plain-English version.
average_cost = total_paid_across_all_buys ÷ total_quantity_bought
In English: if you bought 1 ETH at $2,000 and another 1 ETH at $4,000, you paid $6,000 for 2 ETH. Your average cost is $3,000 per ETH. That number is what Coinlio compares to the live market price when it shows your P&L.
Average cost treats every unit of the same coin as identical — it does not care which one you bought first.
A worked example — 5 transactions, one ETH position
Let us walk through a realistic sequence. You bought Ethereum three times, sold once, and the market moved. Here is what Coinlio shows you after each transaction, and why.
Every number in your portfolio comes from that sequence. If you can follow the steps, you can audit your own P&L at any time.
Edge cases that trip people up
Crypto has more edges than a typical investment. Here is how Coinlio handles the common ones.
| Case | What the app does | What you should know |
|---|---|---|
| Fees on buy | Added to invested (raises cost basis) | A $10 fee on a $2,000 buy gives a cost basis of $2,010 — your real break-even price |
| Fees on sell | Subtracted from proceeds (lowers realized P&L) | A $15 fee on a $2,985 sell leaves you with $2,970 received |
| Partial sell | Pulls at the average, leaves average unchanged | Remaining units keep the same cost basis per coin |
| Full sell then rebuy | Position resets, new average starts from next buy | You are starting fresh — old P&L is realized, new cost basis begins |
| Transferring between wallets | Not a Buy or Sell | Tag as Transfer so it does not change your cost basis |
| Airdrops and rewards | Added at $0 cost by default (you can edit) | Selling later shows as pure profit — correct for tax in most regions but confirm with your local rules |
| Staking rewards | Same as airdrops — $0 cost by default | Edit the cost if your jurisdiction treats rewards as income at receipt |
Why average cost and not FIFO or LIFO?
Average cost is the right default for most retail investors for three reasons.
- Simpler to read. One cost basis per coin, not a stack of individual lots.
- Matches how DCA investors think. If you buy every month, you naturally think in averages.
- Less volatile P&L during small sells. FIFO and LIFO can swing realized P&L dramatically depending on which "lot" the app picks — average cost smooths it.
That said, average cost is not the best method for everyone. Active traders and users in certain tax regimes want to pick exactly which purchase they are selling from. That is what FIFO and LIFO do.
What is coming later — FIFO and LIFO
Coinlio will add FIFO (First In, First Out) and LIFO (Last In, First Out) in a later release, as part of the Pro tier. No hard date yet — we will ship it when we can do it well, not when a marketing plan says we should.
Here is how each one changes the math on the same sell, using the example above.
| Method | How it picks cost basis on a sell | Realized P&L on the 1 ETH sold at $2,985 |
|---|---|---|
| Average cost (today) | Blends all buys into one average | Sell proceeds $2,985 − avg cost $2,343.33 = +$641.67 |
| FIFO (later) | Uses the oldest unsold buy first | Sell proceeds $2,985 − first-buy cost $2,010 = +$975.00 |
| LIFO (later) | Uses the newest unsold buy first | Sell proceeds $2,985 − newest-buy cost (half of the 2-ETH buy) ≈ $2,510 = +$475.00 |
Same trade, three answers. None are wrong — they are different accounting choices. For taxes, your country's rules decide which method you must or may use. For feel, some people want to "sell their oldest coins first" emotionally. Coinlio will let you pick.
How to audit your own P&L in 60 seconds
If a number in Coinlio looks wrong, do this check. It works for any coin, any method.
If it does not match, nine times out of ten it is one transaction — a wrong quantity, a wrong price, or a missing fee. Scroll your transaction list, find the odd one, edit it. The whole portfolio recalculates instantly.
Try Coinlio free — add your transactions and watch every number above recalculate live. <a href="https://apps.apple.com/app/id6761177479">Download on the App Store</a>.
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